1. Field of the Invention
The present invention relates to valve operating mechanism for internal combustion engines which employ the proprietary features of exhaust gas ejectors listed in the cross references.
2. Description of Prior Art
The conventional 4-stroke internal combustion engine uses individual valves to control the flow within the induction and exhaust circuits. The period of operation of each valve in their respective circuits slightly overlap when the engine piston is at the top dead center position of crank rotation, near the end of the exhaust stroke, such that the intake valve begins to open before the exhaust valve has fully closed and the exhust valve is allowed to remain open such that it does not fully close until the piston has passed its top dead center position. Overlapping the period of valve operation improves performance in the conventional engine, particularly in the high sped range where stream inertia becomes more important in the sequencing and separation of events in each circuit. When conventional valving is used in the upper cylinder in conjunction with a lower cylinder side-port ejector the early evacuation of exhaust gases and the induction of air through the ejector, at the bottom of the engine cycle, reduce the inertia of both the exhaust and intake streams flowing in their respective upper cylinder valve port circuits making high speed engine control difficult, when valve overlap is present and standard carburetion techniques are employed. The use of the lower cylinder ejector under these conditions result in the loss of fuel into the exhaust stream and also in exhaust gas dilution of the incoming air-fuel charge which cause manifold burning and backfires as well as the loss of engine speed control. Higher engine temperatures are also experienced because of the lean fuel mixture resulting from the loss of fuel into the exhaust stream and also because of the additional air taken in through the lower cylinder ejector.
In the present invention these problems are eliminated by operating the exhaust gas ejector through an upper cylinder exhaust port such that only one poppet valve per each cylinder is required making the discussion of valve overlap mute. The upper cylinder ejector is designed to function in conjunction with direct or indirect fuel injector systems in place of carburetion. In this respect, some type of engines, such as the dual-cycle systems which are capable of 2-stroke and 4-stroke operation, or dual-fuel engines which use both light and heavy fuels, it is desirable to use both types of fuel injection which increases the versatility of the present invention. In other systems which run at high speeds it is desirable to employ exhaust gas ejectors at both the upper and lower cylinder positions.
In the present invention a combination of engine designs are possible considering direct and indirect fuel injection and by employing an upper cylinder gas ejector singularly or in combination with a lower cylinder gas ejector of which there are several types as described in the cross references.
Most importantly, in the present invention the problem of valve overlap is completely overcome by combining the exhaust and intake lobes of the camshaft into a single broad double-cycle lobe such that the poppet valve is lifted from its seat only once to complete both the exhaust and intake stroke with one single actuation. The double-cycle cam lobe opens the upper cylinder poppet valve at the beginning of the exhaust stroke and it remains fully open throughout the remaining portion of the exhaust stroke such that it is in the fully open position when the intake stroke begins and does not close until the intake stroke is complete. Operating the poppet valve in this manner increases the engines volumetric efficiency and decreases the pressure loads acting on the piston during the exhaust and induction strokes thus reducing the amount of pumping work performed.
Separation of the exhaust and induction streams within the single valve port during the flow reversal when the piston passes the top-dead-center is accomplished by the initial flow dynamics within the gas ejector nozzle and diffuser circuits preventing reversion and subsequent exhaust gas dilution of the air charge.